Conventionally, one method of obtaining 1,3-butadiene is by extraction from a crude C4 stream produced as a co-product of steam cracking. Because 1,3-butadiene has physical properties that are close to other C4 species in such crude C4 streams, extractive distillation is often utilized to separate 1,3-butadiene from the other C4 species. Such extractive distillations typically utilize solvents, such as N-methylpyrollidone or acetone.
Another conventional method of obtaining 1,3-butadiene is by dehydrogenation of n-butane and butenes. For example, 1,3-butadiene may be prepared industrially by the so-called CATADIENE® (Houdry) process. Such a process generally involves dehydrogenation of n-butane or 1-butene and 2-butenes over a fixed or fluidized catalyst.
Additionally, 1,3-butadiene may be obtained by conversion of ethanol. For example, 1,3-butadiene may be produced by the Lebedev method, in which ethanol is converted catalytically to 1,3-butadiene. Such methods generate byproducts including hydrogen and water.